Process of manufacturing yeast



June 25, 1929. L. LAVEDAN 1,718,910

PRocEss oF MANUFACTURING YEAST Filed July l, 1925 PURE YEAST APPARATUSv- INVENTOR lucien lavada,

BY/ww Q@ ATTORNEYS Patented June A25, 1929.

LUCIEN IIAVEDAN,` 0F NEW ORLEANS, LOUISIANA.

PROCESS 0F IANUFAGTURING YEAST.

appueatmn'mea my 1,

My V.invention relates to improvements in processes of lnanufzwturingyeast and it consists in the use of carbon dioxide, CO2, in the variousstages and steps taken during yeast propagation and after thepropagation has been complet-ed, and also in the subsequent productionof carbonated yeast whether 1iq uid, compressed, or dried.

The primary object of vmy invention is to provide a process in whichcarbon dioxide is employed to more effectively carry out in the mostsuitable and etlicient manner, the' continuous process of making yeastwith continuous aeration in propagating pure yeast in a pure sugaredliquid of a given density in the presence of nutritive salts and air;with the separation of the scum containing the yeast thus propagatedJfrom the main body of the liquid, and subsequent separation of theyeast cells from the associated liquid o the scum, with the addition ofsuflicient sugared solution to the separated liquid to bring the mainsugared solution to its original density when the separated liquid isreturned to it, as described in my Letters Patent- No. 1,201,062, on acontinuous process with continuous aeration, granted October 10, 1916,the cold carbon dioxide acting as a suitable agent to neutralize anexcessof alkalinity, and at the same time operating to reduce thetemperature of the Wort.

Another object of`my invention is to provide a process to produce from agiven amount of raw materials, the highest possible yield of yeastpossessing an increased vitality and strength for baking, fermenting,diet and any other uses, while simultaneously decreasing the productionof alcohol.

A further object of my invention is to produce yeast Whichwill keep fora longer period of time than yeast produced by other processes andmethods.

A further object of my invention is to produce yeast possessing a highervitamine and nutrient value, and far more suitable to be used for eatingpurposes as it is more adapted to conditions existing in the humanstomach, more palatable and of better odor and taste, and possesses amore effective action than any other yeast produced by other processesand methods.

AI further object of my invention is to provide a process to reduce orneutralize in a ready, prompt and-eiicient manner an excess ofalkalinity in the Wort at any stage of yeast 1925. Serial No. 40,924.

propagation as Well as when and after it is completed.

A further object of my invention is to provide a process in which anacid reaction is produced 1n the most efficient manner in the wort atany stage of yeast propagation as well as when and after it iscompleted.

A still further object ot' my invention is to provlde a process in whicha most desirable, suitable and eiiicient agent is employed such ascarbon dioxide, to .reduce promptly the temperature of the wort orliquid in incipient fermentatlon at any desirable stage of yeastpropagation and also to maintain the liquid at such temperature.

A further object of my invention is to provide a process in which themost desirable, smtable and efficient agent is employed such as usingcarbon dioxide to reduce promptly the temperature of the Wort to anydesirable temperature, after the yeast propagation is completed.

'A further object of my invention is to provide a process in which aneiicient agent or agents 1s employed, such as any suitable innocuousalkali, carbonate, calcium salt, chalk, or any suitable combination ofthese agents, to neutralize first the Wort and then provide an acidreaction by means of carbon dioxide'at any stage of yeast propagation orafter the propagation has been completed.

A further object of my invention is to provide a process in which a veryefficient agent or agents such as any suitable alkali, carbonate,calcium salt, chalk, or any suitable combination of same, is used forneutralizing the acidity in the Wort and producing a slight alkalinity,and in which carbon dioxide is employed in order to acidity slightlysaid slight alkalinity in a prompt and efficient manner in the Wortafter the yeast propagation is completed, and then subsequentlyproducing a certain low degree of acidity and a predetermined low degreeof temperature in the wort, thus providing for a most desirableflocculation, settling and precipitation of the yeast.

A further object of my invention is to provide a process in which a mostsuitable refrigerating and protecting agent, such as carbon dioxide, isused to reduce oxidation, hydrolysis and decomposition of the yeast fora long period of time as hereafter mentioned; to reduce the acidreforming powers of' the yeast during along period of time; to reducevthe aspiratlon and subsequent oxidation of the yeast during a longperiod of time; to innutrient coating all around the yeast cake ofsuitable nutrient and activating substances to supply the cells withfood when the yeast shall resume its activity, said coating alsosutlicient-ly insulating the yeast cells to prevent said cells fromcoming in direct contact with a refrigerating agent which would injurethe cells.

A still further obj ect is to provide a process with the most suitableand efficient and protective agent, such as carbon dioxide to check theactivity of the compressed yeast, holding its strength and keeping itfresh, of sweet taste and color for a longer period of time than by anyother process, uses and methods.

Other objects and advantages will appear in the following specification,and the novel features of the invention will be particularly pointed outin the ap ended claims.

I shall now descri ed the process of using carbon dioxide (CO2) in thevarious stages and steps of manufacturing carbonated yeast, givingexamples of the method, manner and means in which it can be carriedout.l

In the drawing:

Figure 1 shows more or less diagrammatically an apparatus for carryingout my process.

Figure 2 is a fragmentary vertical section of a propagating tankconstructed according to the principles of my invention.

The yeast propagating process is carried in a wort of any suitablecomposition made in accordance With the usual methods of manu fact-ure,preferably with the most up to date eicient process of continuousaeration, such as described in my Letters Patent No. 1,201,- O62. Noclaims are made as regards the most suitable and efficient nutrient,activatin acidifying and neutralizing substances use in the productionof the wort, as these and their well balanced proportions are well knownand used for these last thirty years in the manufacture of yeast, andits related industries of pure yeast culture, fermentiu and brewing. Itis to be understood that I employ carbon dioxide (CO2) by itself from asource extraneous of. the carbon dioxide directly produced in the yeastand also in connection with other substances, at any stage of yeastpropagation, also at t-he time it is completed and after it iscompleted. The fiist'stage of my process of using carbon dioxide isreached at such a time of the After testing rapidly the wort for itsdegree of acidity and temperature, the necessary amount of carbonate ofcalcium, ammonia water, sodium hydroxide, etc. is used, not only toneutralize it but also to reach a certain slight alkaline reaction asindicated by a slight alkaline reaction in the wort. I employ only acalcium salt such as bi-carbonate of calcium, calcium carbonate, limewater, or chalk, or such other neutralizing agent, ammonia, ammoniawater, sodium hydroxide or such other alkali which can be neutralizedcompletely by the acids in the propagating wort. At this stage of theprocess it is necessary to neutralize rapidly the wort and render thesame slightl narily to the injection o the carbon dioxide vapor.Therefore it is best to delay the addition to the wort of such inorganicsalts generally used as yeast nutrients in the ropagation process whichgive out free' aci and which would delay a prompt neutralization of thewort and thus render said wort slightly alkaline for a short period oftime. The necessary amount of such inorganic salts can be added as .soonas the wort is rendered slightly alkaline. Such salts that are employedgenerally at this time are ammonium sulphate and potassium sulphate.Those alkaline prelimilcompounds which not onl serve to neutralize theacidity in the wort, ut also supply the assimilable nitrogen requiredfor the production of a good yeast are not employed. However, if thewort at the time requires such substance, it is best to use such whichwill furnish it and at the same time neutralize the acidity of the wort.The usual fractional and necessary amount of such salts are added withadvantage after this ste of my process is accomplished. The above lioldstrue, taking in consideration the composition and conditions of thewort, for the following two or more steps of my process; and moreparticularly for the last one which is made just a little before (15 to20 minutes) the propagation is completed when it is not then a questionof carrying on successfully the propagation for a long length of time,but to produce a yeast which will flocculate, settle and separatepromptly and which is not slimy and deicient in one or other substances,and which p ossesses baking strength and keeping qualities. l

Then, as soon as that certain slight alka` line reaction is reached, thenecessary amount of carbon dioxide (CO2) isinjccted at the bottom of thepropagating tank, to neutralize the alkaline excess for producing acertain slight acid reaction in the Wort, for the objects and purposesherebefore and hereafter specified.

The carbon dioxide gas, compressed to the point of liquefaction, atapproximately a pressure of 950 lbs. to the'square inch or 65atmospheres and supplied from a cartridge 10, is injected and deliveredvery slowly through a perforated pipe 11 to the bottom of a propagatingtank 12. The carbon dioxide from pipe 11 or an expansion chamber mustpass through a protective mat formed of a pair of spaced sheets ofperforated tin 13 and 14, an intermediate 'sheet of felt 15, a sheet oflinen 16 upon each face of the felt, and a copper screen 17 between eachlinen sheet and the sheetof tin. A pure yeast apparatus 18 is connectedwith the tank 12 and is adapted to supply said tank with a selected pureyeast acclimated to propagate eiiciently in a slightly acid wort. Aseparator 19 is employed for the usual purpose.

The construction. shown in Figure 2 prevents the carbon dioxide snowfrom coming in contact with the cells and thus prevents the destructionor material injury to the yeast cells. When the fiuid gas escapes, itssudden expansion causes a rapid fall of its temperature, and itsdelivery at the bottom of the tank has to be regulated on such a ratioof speed and pressurethat a fine pulverized white snow is formed at thebottom of the screen sheet 13 where the carbon dioxide gas Vis liberatedand returns to the expanded gaseous state and bubbles through the liquidyeast or wort, thereby reducing promptly the temperature and thepre-arranged excess of alkalinity. The gas is turned on very slowly topermit the carbon dioxide (CO2) to evaporate through the wort andneutralize its alkaline salts, to such an extent thatl a certain slightacid reaction in the wort is reached.

This first addition 'of alkalies and other substance and injection ofcarbon dioxide is done at such a time when the wort has reached, asbefore said, a too high acidity and temperature, or about 3 to 4 hoursafter starting the propagation. The second addition and injection isdone in the same way and manner as the iirst one, and at such a time itis found necessary, which is about 2 to 3 hours later, and the third orlast one is done just a little before the propagation is completed, inthe same way and manner, taking in consideration what has beenheretofore stated relative to the use of the most suitable neutralizingagent. The exact limit of time when these three or more if necessary,steps have to be taken, vary widely according to many factors in theprocess of propagation, and is determined by observation, testing andpractice.

The objects and results of the steps taken are obvious. It is a matterof fact and of usual knowledge for a generation, that high acidities andhigh temperatures in the process of propagating yeast, have to be andare usually properly reduced. In the necessity of having to reduce theever increasing acidity and free acids, as well as the tempera.- ture ofthe wort, fractional steps are far more desirable and efficient thaneontinuousadditions or continuous reductions, as these are practicallyimpossible to be carried in a suit-l able and efficient manner; and alsobecause yeast cells, Saccharomyces of all species are biological andtherefore do not remain inactive. They must change, that is they live,produce and die, and their following generations possessing most of thetime a much lower vitality and strength, at times necessitate a somewhatdifferent environment and varying conditions.

Briefly stated, yeast cells must be first cultivated and acclimatedgradually or by steps in a certain increasing environment in order toattain an increasing efiicient propagation and this is also true ottheir generations fol` lowing at such a time that the environmentbecomes innocuousand does not propagate efficiently.

It is also a matter of fact and of usual knowledge for the last thirtyyears or more that a selected pure yeast can be cultivated andacclimated to propagate efficiently either in a certain environment orin a Wort of either low or a relatively high acidity, but the cells willvnot propagate in a manner as ef ficiently in a wort of slightalkalinity. Preference has to be given to a slight as possible acidity,particularly in the propagation of yeast for baking, fermenting and dietpur-k poses. High acidity impairs not only the production but also thequality and strength of the yeast cells'. In a slight alkaline wort,their propagation as well as the vitality and strength is comparativelymuch less. Therefore it is more desirable to select, cultivate,acclimate a pure yeast to work efficiently in a slight acidityrearranged from time to time with other varying conditions ot theprocess, and subsequent-ly their generations will be eflicient 1n thefollowing propagating process. The advantages are obvious and numerousin the process and practice of using carbon dioxide to reach a slightacid reaction and reduce promptly the temperature in the propagatingprocess.

Further, my process is not only most et ficient, but also mosteconomical. The quantity of alkali and other stated suitable substances,also the amount of carbon dioxide (CO2) required are very smallcomparatively to the results obtained. For instance. in a wort of aslight acidity such as used in my process, one gramm of caustic soda C.P. per gallon of wort is suflicient to neutralize the acidity and reacha slight alkaline react-ion in the wort. Only a total of 25 lbs. ofcarbon dioxide (CO2) are used in the three fractional steps herebe'foremcntloned.

About 5 lbs. in the first, 5 to l0 inthe second and the balance in thelast step a. little. before the time the process of propagation iscompleted. In the second stage and steps of my process with a properequipment not over 75 lbs. of carbon dioxide (CO2) for a product-ion of2000 lbs. of compressed yeast, are used, and C()2 besides acting as aprotective and agent and for other numerous purposes herebefore 'andhereafter mentioned, acts as a most eilieient ref rigerating agent atthe proper time.

Compressed yeast deteriorates and loses its vitality and strength,particularly so when it is or becomes rapidly highly acid. Variousexperiments carried out to investigate the action of a highly acid yeastupon solutions of calcium lactate and other mineral salts. havedemonstrated that the oxidation of the calcium lactate proceeds rapidlyand is accelerated by increased proportions of ammonium phosphate,calcium and magnesium sulfates, and that the oxidation takes place morerapidly at the surface of the yeast cake than in the inside of it.Lactic acids and others are partly decomposed and in a very short time,and all the carbohydrates of the yeast are partly hydrolized in thepresence of air, and very rapidly if the compressed yeast is not kept ata low temperature, approximately the temperature of freezing water.

The second phase and second steps of my process are carried out inamanner which I shall now describe:

After the compressed `yeast is made in accordance with the usual methodsof manufacture, a certainamount of a dry mixture, preferably powdered ora solution amounting to about 10% of the weight of the compressed yeast,is made of sugar, a calcium salt, an ammonium salt or any other suitablesubstances. I use preferably 3% of the weight of compressed yeast incalcium phosphate; 2% in'annnonium tart-rate, and 5% in powderedinverted sugar.

Before wrapping up the yeast cake, a certain amount of the aboveingredients, approximately 10% of the weight of said yeast cake, iscoated all around the surface of the said compressed yeast cake. Thecakes are wrapped up with clean linen or muslin, gauze and set in rows,each cake being slightly spaced from another and then frozen by carbondioxide (CO2) in an ice box specially built for that purpose.

Then the carbon dioxide (CO2) under pressure, is turned on very slowlyand -delivered at the bottom of each row of the yeast cakes to freezethem on the surface in such a manner until they are coated with carbondioxide snow and until the yeast cakes are almost perfectly hard. Whenthis is done, the yeast cakes will remain hard for hours depending onthe hardness of the carbon dioxide snow.

This hardness gives ample time for removing the frozen yeast cakes andfor placing them in -ardboard boxes or other containers without beingmaterially affected by the outside temperature when said cakes may beput into an ice box -or packed for shi ment with ice, preferably withcarbon dioxi e ice.

This is preferably done after coating the compressed yeast cake with adry mixture or a solution of insulating, protecting as well as nutrientsubstances as previously described. However, in using carbon dioxidewith discretion, this can also bedone without said dry mixture, and theyeast can be carefully wrapped up with muslin tissue paper or othersufficient, partially or totally insulatin materials, and the freezingof the yeast wit 1 carbon dioxide (CO2) can be effected, if not in aperfect manner and condition, at least in a sutlicient suitable manner.Therefore, I claim the use of carbon dioxide to freeze and keep theyeast although this should not be coated with the protective andnutrient mixture as hereabove specified.

Carbon dioxide as the final treatment may be applied in different waysand methods, taking however in due consideration that it is essential tohave a certain coating all around the. yeast cake, so as to not destroythe yeast cells by contact with carbon dioxide snow. The center of theyeast cake must be only slightly frozen. The yeast cells are there atrest, hibernating in the slightly frozen mass, and will start life againwith renewed vigor and activity, when the mass shall be allowed to thawand the temperature rises again. The longer the pressure of carbondioxide (CO2) is maintained, the deeper the freezing penetrates. Thesurface of the yeast cake is only required to be frozen sutlicientlyhard as before stated. Carbonated yeast, that is yeast so treated, willretain its baking strength as well as all other qualities about twomonths, and much longer if kept in suitable ice boxes, preferably carbondioxide ice.

rith the use of carbon dioxide in addition to the advantages herebeforestated, there is also the big advantage in reference to the cakingquality of the yeast so treated in conjunction with calciuln salts, ofabsorption of moisture without heating, and this absorption eHiciency,will keep the compressed yeast under a 10% moisture content. The carbondioxideI (CO2) snow returning to the gaseous state, furnishes a carbondioxide environment to the mass of the yeast, checking respiration,reactions, 'dccon'ipositiom moulding, re-forming of acids and theactivity of the yeast. It keeps the yeast fresh, of sweet taste andcolor, until such a time it shall be allowed to become active and beused.

The yeast in liquid form may be bottled and when in such condition saidyeast may be impregnated with carbon dioxide gas with the results asstated above.

'lill What I claim is:

l. A stepV in the process of propagating yeast Whichcomprises injectinginto the yeast wort, before the temperature has been appreciably raised,cold vapors formed by the evaporation of liquid carbon-dioxide.

2. A step in the processof propagating yeast which comprises addingslightly in excess neutralizing agents to a yeast wort having an'acidreaction to produce an alkaline reaction, then injecting cold carbondioxide into the wort before the temperature thereof has-beenappreciably raised to produce a low degree of acidity.

3. A step in the process of propagating yeast which comprises addingslightly in excess neutralizing agents to a yeast wort having an acidreaction to produce an alkaline reaction, then injecting into the yeastVwort before the temperature thereof has been appreciably raised, coldvapors formed by the evaporation of liquid carbon dioxide to produce alow degree of acidity and temperature.

. 4. A step in the process of propagating yeast which comprises addingslightly in excess neutralizing agents to' a yeast wort having an acidreaction to produce an alkaline reaction, then after yeast cells havebeen propagated injecting into theyeastwort cold vapors of carbondioxide before the temperature thereof has been appreciably raised, tocause flocculation,'settling and precipitatibn of yeast cells. l

5. A step in the process of propagating yeast which comprises addingslightly neutralizing agents to a yeast wort having an acid reaction toproduce an alkaline reaction, then after yeast cells have beenpropagated injecting into said yeast wort before the temperature hasbeen appreciably raised, cold vapors formed by the evaporation of liquidcarbon dioxide and then injecting at intervals more cold vapors formedby the evapora;- tion of liquid carbon dioxide linto the yeast wort.

6. A step in the process ofpropagating yeast which comprises injectinginto the bottom of a column of yeast wort having a slight acid reactionbefore the temperature thereof has been appreciably raised, cold vaporsformed by the evaporation of liquid carbon dioxide for progressivelycooling the column of yeast propagating wort. Y

7. A step in the process of propagating yeast which comprises addingneutralizing agents to a column of yeast wort having a slight acidreaction to produce an alkaline reaction, then injecting into the bottomof' the column of the yeast wort before the temperature thereof has beenappreciably raised, cold vapors formed by the evaporation of liquidcarbon dioxide for progressively cooling the column of yeast propagatingwort.

8. A process of propagating yeast which comprises treating a wort whichhas a too high acid reaction and a too high temperature for thepropagation of yeast cells during the propagation of yeast therein, withan alkaline reagent while changing the acidity of the wort to a slightalkalinity, cooling the wort with cold vapors formed by expandingliqueedcarbon dioxide while changingV the alkaline reaction of the wortto a slight acid reaction. j

9. A step in the process of propagating yeast which comprisesimpregnating a liquid in incipient fermentation such as a yeastpropagating wort having a slight alkaline reaction with compressedcarbon dioxide when the compressed carbon dioxide is expandedundervpressure while controlling the temperature of the liquid andcontinuing the treatment with the carbon dioxide until the liquid showsa slight acid reaction.

10. A step in the process of propagating yeast which lcomprisesimpregnating at intervals a liquid in incipient fermentation such as ayeast propagating wort, having a slight alkaline reaction withcompressed carbon dioxide when said carbon dioxide is expanding underpressure and controlling the temperature of vthe, liquid and continuingthe treatment with carbon dioxide until the liquid shows a slight acidreaction.

1l. A step in the process of propagating yeast which comprises-chillinga liquid in incipient. fermentation such as a yeast'propagating worthaving a slight alkaline reac- Vtion by forcing the cold gases andvapors from expanding liquefied carbon dioxide 'through said liquiduntil said liquid shows a slight acid reaction.

12. A step in the process of propagating yeast which comprises treatinga liquid in incipient fermentation such as a yeast propagating worthaving a slight acid reaction with an alkaline reagent until said liquidshows a slight alkaline reaction, cooling the Wort by impregnating theliquid having a slight alkaline reaction with carbon dioxide having a.temperature less than the temperature of the liquid while changing thealkaline reaction Ato a slight acid reaction.

13. A step in the process of propagating yeast which comprises adding analkaline reaction producing substance to a wort which has a slight acidreaction until said wort shows a slight alkaline reaction, expandingcold compressed carbon dioxide in the wort While at the same timeimpregnating the wort with cold gas and vapors of the carbon dioxideuntil said wort shows a slight acid reaction and a reduction intemperature of the wort.

14. A step in the process of propagating yeast which comprises adding analkaline reaction producing substance to a wort having an acid reactionwith a calcium compound to change the Wort to a slight alkaline reactionand then impregnating the Wort with expanded cool gases and vaporsformed by expanding compressed carbon dioxide to cause a slight acidreaction vand a temperature reduction.

'15. A step in the process of propa ating yeast which comprisesexpanding col compressed carbon dioxide, injecting the expanded carbondioxide vapors into a yeast propagating wort below the temperature ofsaid Wort While at the same time raising the temperature of the carbondioxide to protect the yeast cells fromfreezing during the injection.

16. A step in the process of propagating yeast which comprises adding analkaline reaction producing substance to a yeast propagating wort havinga slight acid reaction until said wort shows a slight alkaline reactionand before the ropagation of the yeast cells have been comp eted, theninjectin cold carbon dioxide vapors into the wort W ich has a slightalkaline reaction to change such reaction to a slight acid while at thesame time lowering the temperature of the wort below that of atmosphericfor producing a yeast which will occulate, settle and be easilyseparated.

LUCIEN LAVEDAN.

